In a wireless communication system, a system performance and capacity deteriorate due to phenomenon such as an interference occurring between cells or inside cells, multi-path fading, the Doppler effect, and the like. One of techniques for increasing a system capacity by addressing the above-listed performance deteriorating factors is a beamforming technique. The beamforming technique is one of smart antenna schemes, and increases a signal gain at a reception end by properly combining phases and sizes of signals transmitted, respectively, via a plurality of antennas. Generally, the beamforming technique is realized by using four or more transmission antennas. That is, to apply the beamforming technique, the transmission end needs to have four or more transmission antennas.
Presently, base stations having two transmission antennas have been developed. However, since four or more transmission antennas are required in order to apply the beamforming technique, a Radio Unit (RU) having two Radio Frequency (RF) paths of the base stations needs to be replaced by an RU having four or more RF paths. In this case, the RU having the two RF paths is not utilized and redundancy in a hardware resource occurs. Therefore, to prevent redundancy in the hardware resource, an alternative for realizing a 4-beamforming technique using an RU having two RF paths is required.